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| United States Patent |
5,692,988
|
|
Beim
, et al.
|
December 2, 1997
|
Multiple-speed automatic transmission for an automotive vehicle
Abstract
A kinematic arrangement of a multiple-speed automatic transmission for an
automotive vehicle includes a simple planetary gear unit and a compound
planetary gear unit, hydraulically actuated clutches and brakes applied
and released selectively, and an overrunning clutch that produces a
one-way drive connection between the carrier of the first gear unit and a
nonrotating member such as the transmission casing. The simple planetary
gear unit includes a sun gear, a ring gear surrounding the sun gear, a
carrier, and a set of planet pinions in continuous meshing engagement with
the sun gear and ring gear and rotatably supported on the carrier. The
compound gear unit includes a sun gear, a ring gear surrounding the sun
gear, a carrier, a first set of planet pinions in continuous driving
engagement with the sun gear, and a second set of planet pinions in
continuous engagement with the ring gear and the first set of planet
pinions.
| Inventors:
|
Beim; Rudolf (Bloomfield Hills, MI);
McCarrick; Daniel W. (Canton, MI)
|
| Assignee:
|
Ford Global Technologies, Inc. (Dearborn, MI)
|
| Appl. No.:
|
653181 |
| Filed:
|
May 24, 1996 |
| Current U.S. Class: |
475/281; 475/280; 475/284; 475/285; 475/286; 475/287 |
| Intern'l Class: |
F16H 003/62 |
| Field of Search: |
475/280,281,284,285,286,287
|
References Cited
U.S. Patent Documents
| 4483215 | Nov., 1984 | Ishimaru et al. | 475/280.
|
| 5007887 | Apr., 1991 | Asada | 475/280.
|
| 5141477 | Aug., 1992 | Oshidari | 475/280.
|
Other References
SAE 930676, "A New Approach to Finding Optimum Planetary Gear Trains for
Automatic Transmissions ", Oshidari et al, Mar. 1-5, 1993.
|
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Jensen; Nathan O.
Attorney, Agent or Firm: McKenzie; Frank G.
Claims
We claim:
1. A multiple-speed transmission comprising:
an input shaft;
an output shaft;
a first planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and first and second sets of pinions supported
rotatably on the carrier, the first set of pinions driveably engaged with
the sun gear and second set of pinions, the second set of pinions
driveably engaged with the ring gear and first set of pinions;
a second planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and a third set of pinions supported rotatably on the
second carrier and driveably engaged with the sun gear and ring gear of
the second gear unit, the sun gear of the first gear unit continually
driveably connected to the input shaft, the ring gear of the second gear
unit continually driveably connected to the output shaft, the carrier of
the first second gear unit and sun gear of the second gear unit
continually driveably connected mutually;
a first clutch for alternatively driveably connecting and releasing the
ring gear of the first gear unit and the carrier of the second gear unit;
a first brake for alternately holding against rotation and releasing the
carrier of the first gear unit; and
an overrunning coupling for producing a one-way drive connection between
the carrier of the second gear unit and a nonrotating member.
2. The transmission of claim 1, wherein the overrunning coupling further
comprises:
a first race continually driveably connected to the carrier of the second
gear unit, and first clutch,
a second race fixed to the nonrotating member; and
a drive member located between the first and second races for producing a
one-way drive connection between the first and second races.
3. The transmission of claim 1, further comprising a second clutch for
alternatively driveably connecting and releasing the input shaft and
carrier of the second gear unit.
4. The transmission of claim 3, further comprising a second brake for
alternately holding against rotation and releasing the ring gear of the
first gear unit.
5. The transmission of claim 1, further comprising:
a third clutch for alternatively driveably connecting and releasing the
carrier of the first gear unit and input shaft; and
a third brake for alternately holding against rotation and releasing the
ring gear of the second gear unit.
6. A multiple-speed transmission comprising:
an input shaft;
an output shaft;
a first planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and first and second sets of pinions supported
rotatably on the carrier, the first set of pinions driveably engaged with
the sun gear and second set of pinions, the second set of pinions
driveably engaged with the ring gear and first set of pinions;
a second planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and a third set of pinions supported rotatably on the
second carrier and driveably engaged with the sun gear and ring gear of
the second gear unit, the sun gear of the first gear unit continually
driveably connected to the input shaft, the ring gear of the second gear
unit continually driveably connected to the output shaft, the carrier of
the first second gear unit and sun gear of the second gear unit
continually driveably connected mutually;
a first clutch for alternatively driveably connecting and releasing the
ring gear of the first gear unit and the carrier of the second gear unit;
a second clutch for alternatively driveably connecting and releasing the
input shaft and carrier of the second gear unit;
a first brake for alternately holding against rotation and releasing the
carrier of the first gear unit; and
an overrunning coupling for producing a one-way drive connection between
the carrier of the second gear unit and a nonrotating member.
7. The transmission of claim 6, wherein the overrunning coupling further
comprises:
a first race continually driveably connected to the carrier of the second
gear unit, and first clutch,
a second race fixed to the nonrotating member; and
a drive member located between the first and second races for producing a
one-way drive connection between the first and second races.
8. The transmission of claim 6, further comprising:
a third clutch for alternatively driveably connecting and releasing the
carrier of the first gear unit and input shaft; and
a second brake for alternately holding against rotation and releasing the
carrier of the second gear unit.
9. The transmission of claim 8, further comprising a third brake for
alternately holding against rotation and releasing the ring gear of the
first gear unit.
10. A multiple-speed transmission comprising:
an input shaft;
an output shaft;
a first planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and first and second sets of pinions supported
rotatably on the carrier, the first set of pinions driveably engaged with
the sun gear and second set of pinions, the second set of pinions
driveably engaged with the ring gear and first set of pinions;
a second planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and a third set of pinions supported rotatably on the
second carrier and driveably engaged with the sun gear and ring gear of
the second gear unit, the sun gear of the first gear unit continually
driveably connected to the input shaft, the ring gear of the second gear
unit continually driveably connected to the output shaft, the carrier of
the first second gear unit and sun gear of the second gear unit
continually driveably connected mutually;
a first clutch for alternatively driveably connecting and releasing the
ring gear of the first gear unit and the carrier of the second gear unit;
a second clutch for alternatively driveably connecting and releasing the
input shaft and carrier of the second gear unit;
a first brake for alternately holding against rotation and releasing the
carrier of the first gear unit;
a second brake for alternately holding against rotation and releasing the
carrier of the first gear unit; and
an overrunning coupling for producing a one-way drive connection between
the carrier of the second gear unit and a nonrotating member.
11. The transmission of claim 10, wherein the overrunning coupling further
comprises:
a first race continually driveably connected to the carrier of the second
gear unit, and first clutch,
a second race fixed to the nonrotating member; and
a drive member located between the first and second races for producing a
one-way drive connection between the first and second races.
12. The transmission of claim 11, further comprising:
a third clutch for alternatively driveably connecting and releasing the
carrier of the first gear unit and input shaft; and
a third brake for alternately holding against rotation and releasing the
ring gear of the first gear unit.
13. A multiple-speed transmission comprising:
an input shalt;
an output shaft;
a first planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and first and second sets of pinions supported
rotatably on the carrier, the first set of pinions driveably engaged with
the sun gear and second set of pinions, the second set of pinions
driveably engaged with the ring gear and first set of pinions;
a second planetary gear unit supported on a first axis, having a sun gear,
ring gear, carrier, and a third set of pinions supported rotatably on the
second carrier and driveably engaged with the sun gear and ring gear of
the second gear unit the sun gear of the first gear unit continually
driveably connected to the input shall, the ring gear of the second gear
unit continually driveably connected to the output shaft, the carrier of
the first second gear unit and sun gear of the second gear unit
continually driveably connected mutually;
a first clutch for alternatively driveably connecting and releasing the
ring gear of the first gear unit and the carrier of the second gear unit;
a second clutch for alternatively driveably connecting and releasing the
input shaft and carrier of the second gear unit;
a first brake for alternately holding against rotation and releasing the
carrier of the first gear unit; and
a second brake for alternately holding against rotation and releasing the
carrier of the first gear unit.
14. The transmission of claim 13, further comprising:
a third clutch for alternatively driveably connecting and releasing the
carrier of the first gear unit and input shaft; and
a third brake for alternately holding against rotation and releasing the
ring gear of the first gear unit.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of automotive transmission kinematics.
More particularly, it pertains to an arrangement of clutches, brakes, and
planetary gear units for an automatic transmission.
2. Description of the Prior Art
Conventional transaxles include an hydrokinetic torque converter and a
gearing system arranged either coaxially with the torque converter axis or
parallel to that axis. In transaxles of this type, it is important that
various torque transfer elements be arranged so that they occupy minimal
space, particularly along the transverse of the motor vehicle. Gearbox
length along that axis is minimized to permit the transaxle to be located
in a front-wheel drive vehicle, one in which the engine and transmission
are located in a compartment restricted in a transverse or lateral
direction by chassis constraints, vehicle styling requirements, etc.
In addition, there is a growing need to develop more compact automatic
transmission gear arrangements with an increasing number of speed ratios
in order to realize better fuel economy and to improve driveability. The
transmission described in SAE Technical Paper 930676 describes a
relatively compact gear arrangement requiring three hydraulically actuated
friction clutches and two hydraulically actuated friction brakes to
produce five forward speed ratios and a reverse drive. Normally, five
forward speed ratios and a reverse drive would require three simple
planetary gear units. However, when five forward speed ratios can be
produced using only two planetary gear units, there is a savings in the
transverse dimension of the gearbox.
SUMMARY OF THE INVENTION
Objects of the kinematic arrangement of the present invention are to
provide five forward speeds and reverse drive and to reduce the number of
planetary gear units from three to two. An advantage of this invention is
improvement in the packaging flexibility of the gearbox. This reduction in
number of gear units is particularly important in transmissions where the
output shafts must pass through the planetary gear units to the drive
wheels.
In realizing these objects and advantages, the multiple-speed transmission
of this invention includes an input shaft, an output shaft, and first
compound planetary gear unit, and a second simple planetary gear unit. The
first planetary gear unit includes a sun gear, ring gear, carrier, and
first and second sets of pinions supported rotatably on the carrier, the
first set of pinions driveably engaged with the sun gear and second set of
pinions, the second set of pinions driveably engaged with the ring gear
and first set of pinions. The second planetary gear unit includes a sun
gear, ring gear, carrier, and a third set of pinions supported rotatably
on the carrier and driveably engaged with the sun gear and ring gear of
the second gear unit. The sun gear of the first gear unit is continually
driveably connected to the input shaft, the ring gear of the second gear
unit is continually driveably connected to the output shaft, the carrier
of the first second gear unit and sun gear of the second gear unit are
continually driveably connected mutually.
The gear units are controlled by several hydraulically-actuated friction
elements, including a first clutch for alternatively driveably connecting
and releasing the ring gear of the first gear unit and the carrier of the
second gear unit, a second clutch for alternatively driveably connecting
and releasing the input shaft and carrier of the second gear unit, a first
brake for alternately holding against rotation and releasing the carrier
of the first gear unit, a second brake for alternately holding against
rotation and releasing the carrier of the first gear unit, a third clutch
for alternatively driveably connecting and releasing the carrier of the
first gear unit and input shaft, and a third brake for alternately holding
against rotation and releasing the ring gear of the first gear unit.
To provide nonsynchronous gear changes between first and second gears, an
overrunning coupling is included to produce a one-way drive connection
between the carrier of the second gear unit and a nonrotating member such
as the transmission casing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 is schematic diagram of a kinematic arrangement of an automatic
transmission according to the present invention.
FIG. 2 is a chart showing the state of the friction elements of FIG. 1
corresponding to each of the speed ratios of the transmission according to
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, an engine crankshaft 10 is driveably connected through
various shafts, hydraulically actuated friction clutches and brakes, and
multiple planetary gear units to an output shaft 12, which is adapted for
connection to the traction wheels of a motor vehicle through a final drive
gearset, differential, driveline, and axle assemblies. The main
transmission housing encloses planetary gear units 14, 16.
An hydrokinetic torque converter 18 includes a bladed impeller 28, a bladed
turbine 30, and a bladed stator 32. The impeller, turbine, and stator are
arranged in fluid flow relationship in a common toroidal circuit. The
impeller includes a casing 34 connected driveably to crankshaft 10.
Turbine 30 includes turbine hub 36 splined to turbine shaft 38. The stator
wheel is supported on the outer race 41 of a one-way clutch 42, whose
inner race 44 is fixed to a nonrotating shaft or the transmission housing.
Clutch 42 produces a drive connection between the nonrotating member and
the stator wheel in a first directional sense and overruns allowing free
rotation of the stator wheel relative to the nonrotating member in the
opposite directional sense.
Torque converter lockup clutch 46 is splined to turbine shaft 38 and
carries a friction surface, located at its radially outer end to engage
driveably with the torque converter casing 34. Lockup clutch 46 is engaged
to complete a mechanical connection between the impeller and turbine when
pressurized hydraulic fluid contained in the torque converter casing
forces the friction surfaces of clutch 46 against the casing 34. The
torque converter is disengaged so that an hydrodynamic driving connection
exists between the impeller and turbine when pressurized hydraulic fluid
is supplied through a passage located between the converter casing and the
friction surfaces of clutch 46 to disengage the clutch.
Power is transmitted by a belt or chain drive mechanism from the axis of
the crankshaft 10 and turbine shaft 38 to a parallel axis colinear with an
input shaft 40, about which planetary gear units 14, 16 and the clutches,
brakes, and shafts of the kinematic arrangement are located. The drive
mechanism includes a first sprocket wheel 45, rotatably mounted on turbine
shaft 38, a second sprocket wheel 47, rotatably supported about the axis
of input shaft 40, and a drive belt or chain 48 driveably engaged with
sprocket wheels 45, 47. 40, a ring gear 52 surrounding the sun gear, a
pinion carrier 54, a first set of planet pinions 56 driveably engaged with
ring gear 50, and a second set of planet pinions 58 continually driveably
engaged with ring gear 52 and the first set of planet pinions 56.
The second planetary gear unit 16 includes sun gear 60, carrier 62, a ring
gear surrounding the sun gear and carrier, and a set of planet pinions 66
continually driveably engaged with ring gear 60 and sun gear 64.
Ring gear 60 is continually driveably connected through member 68 to
carrier 54 of the first planetary gear unit, and ring gear 64 of the
second planetary gear unit is connected through member 70 to output shaft
12.
Overrunning coupling 72 includes an inner race continually driveably
connected to carrier 62 and an outer race fixed and held against rotation
on the transmission casing 74. Located between the inner and outer races
of the coupling are a set of rollers or sprags, which driveably engage the
inner and outer races to produce a one-way drive connection between
carrier 60 and the transmission casing when rotation is in one direction.
One-way clutch 72 overruns when the directional sense of rotation is in a
second direction, opposite the first direction.
A first hydraulically-actuated friction clutch 76 is engaged to produce a
driveable connection among ring gear 52, carrier 62, and the inner race of
one-way clutch 72, and is disengaged to permit those components to turn
freely.
A second hydraulically-actuated friction clutch 78 is engaged to produce a
driveable connection between input shaft 40 and carrier 62 of the second
planetary gear unit 16, and is disengaged to permit free rotation of
carrier 62 relative to shaft 40.
A third hydraulically actuated friction clutch 80 is engaged to produce a
driveable connection between input shaft 40 and the carrier 54 of the
second planetary gear unit 14, and is disengaged to permit shaft 40 to
turn relative to the carrier 54.
A first hydraulically actuated friction brake 82 driveably connects and
releases carrier 54 from the transmission housing 74 or another
nonrotating member when the clutch is engaged and permits carrier 54 to
turn freely when brake 82 is disengaged. A second hydraulically actuated
friction brake 84 holds ring gear 52 against rotation when the brake is
engaged and permits ring gear 52 to turn freely when the brake is
disengaged. A third hydraulically actuated friction brake 86 holds carrier
62 against rotation, driveably connecting the carrier to housing 74 when
the brake is engaged, and permits carrier 62 to turn freely when brake 86
is disengaged.
In operation, the first forward gear ratio is produced by engaging clutch
76, thereby driveably connecting ring gear 52 through clutch 76 and
one-way clutch 72 to the transmission housing. Similarly, carrier 62 of
the second planetary gear unit is held against rotation on the
transmission housing through the driveable connection produced by one-way
clutch 72. Sun gear 50 is driven directly by input shaft 40, and carrier
54 is underdriven in relation to the speed of input shaft 40 and its
direction of rotation is reversed through gear unit 14. With carrier 62
held against rotation and sun gear 16 underdriven in the reverse
direction, output is taken at ring gear 64, and output shaft 12 is driven
in the forward direction at a still further speed reduction in relation to
the speed of input shaft 40.
An upshift to the second speed ratio is produced by maintaining clutch 76
engaged and by engaging first brake 82, which holds carrier 54 of the
first gear unit 14 and sun gear 60 of the second gear unit 16 fixed
against rotation. The output of gear unit 14 is taken at ring gear 52,
which is driveably connected through clutch 76 to carrier 62, which is
underdriven in relation to the speed of input shaft 40. With sun gear 60
held fixed against rotation and carrier 62 driving, the output is taken at
ring gear 64 and output shaft 12, thereby producing a somewhat lower speed
reduction than at first forward ratio.
An upshift to the third forward speed ratio occurs by disengaging brake 82
and engaging clutch 78 while maintaining clutch 76 engaged. Ring gear 52
is driven at the speed of input shaft 40 through engagement of clutches 76
and 78, and sun gear 50 is continually driveably connected to the input
shaft 40. Therefore, the output of gear unit 14 is taken at carrier 54,
which drives sun gear 60 at the speed of the input shaft. Consequently,
ring gear 64 and output shaft 12 are driven at the speed of the input
shaft since sun gear 60 and carrier 62 of gear unit 16 are driven at that
speed.
An upshift to the fourth speed ratio results by disengaging clutch 76,
maintaining clutch 78 engaged, and by engaging first brake 82. This action
overdrives ring gear 64 and output shaft 12 in relation to the speed of
input shaft 40 because sun gear 60 is held fixed against rotation through
operation of brake 82, and carrier 62 is driven at the speed of input
shaft 40 through engagement of clutch 78.
An upshift to the fifth speed ratio results by maintaining clutch 78
engaged, disengaging brake 82, and engaging brake 84. Carrier 54 of the
first gear unit is underdriven in a reverse direction due to ring gear 52
being held fixed against rotation by brake 84 and sun gear 50 being
driveably connected to input shaft 40. Therefore, sun gear 60 is
underdriven at the speed of carrier 54. Input shaft 40 drives carrier 62
of the second gear unit 16 due to engagement of clutch 78; therefore, ring
gear 64 and output shaft 12 are overdriven in the forward direction by the
second gear unit in relation to the speed and direction of shaft 40.
To produce reverse drive, reverse clutch 80 and reverse brake 86 are
engaged concurrently, and the other friction elements are disengaged. Sun
gear 60 of the second planetary gear unit 16 is driven at the speed of
input shaft 40 through carrier 54 and clutch 80. Brake 86 holds carrier 62
fixed against rotation; therefore, ring gear 64 and output shaft 12 are
underdriven in the reverse direction in relation to the speed and
direction of input shaft 40.
Although the form of the invention shown and described here constitutes the
preferred embodiment of the invention, it is not intended to illustrate
all possible forms of the invention. Words used here are words of
description rather than of limitation. Various changes in the form of the
invention may be made without departing from the spirit and scope of the
invention as disclosed.
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